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Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst - AQA - A-Level Biology - Question 1 - 2021 - Paper 1
Question 1
Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst. 1. The substrate binds to the active site of the enzyme, forming an enzyme-sub... show full transcript
Worked Solution & Example Answer:Describe the induced-fit model of enzyme action and how an enzyme acts as a catalyst - AQA - A-Level Biology - Question 1 - 2021 - Paper 1
Step 1
Describe the induced-fit model of enzyme action
Answer
The induced-fit model of enzyme action posits that the enzyme does not have a rigid shape. Instead, when the substrate approaches the enzyme, it induces a change in the enzyme's shape, allowing for a better fit between the enzyme's active site and the substrate. This mechanism contrasts with the lock-and-key model, where the shape is seen as static. The induced-fit model highlights the dynamic nature of molecular interactions and explains how enzymes can lower activation energies by straining substrate bonds.
Step 2
How an enzyme acts as a catalyst
Answer
An enzyme acts as a catalyst by providing an alternative reaction pathway with a lower activation energy. This is achieved primarily through the formation of enzyme-substrate complexes, where the substrate is held in position by various interactions such as hydrogen bonds, ionic bonds, or van der Waals forces. Consequently, once bound, the reaction can occur more rapidly as the enzyme stabilizes the transition state, ultimately leading to the products' formation without altering the enzyme's own structure in the process.